There are presently available many different types of storage shelf systems. The most common of these systems is one which comprises horizontal shelf panels bolted or screwed to upright support members at the four corners of the shelf panels. Typically these systems suffer from the drawback that they are awkward to put together and once assembled, are very unstable due to the pivotal-type connections at the four corners of the shelf panel with the upright supports.
Other types of systems have been proposed in which the shelf panel is provided with a downturned flange adapted to fit within a tongue provided on the upright support. However, these proposed systems also suffer from drawback in that the entire structure is dependent upon the strength of the tongue on the support member which is susceptible to collapsing under any substantial load.